The present invention relates to the high speed printing industry, and more particularly a system and method for flowing variable data into a page description language file in a high speed printing environment.
Application programs, such as word processors, illustrators, and computer-aided design systems are software packages used to create a document (text and graphics) on a computer screen and to simultaneously generate a page description language ("PDL") specification, which is to be transferred to the printer or to any other type of raster or output device for creating a hard copy or copies of the document. Alternatively, a PDL specification can be generated by a programmer without the assistance of an application program.
The printer executes the PDL specification to generate a bitmap of the document, or a raster-data representation of a document, and eventually transfers the bitmap or raster-data to the physical medium. A typical PDL language, such as PostScript (a registered trademark of Adobe Corporation) defines a page of the document as containing a number of data areas, where each data area contains either graphic or alpha-numeric data. Each data area is defined by a "graphic state," which is a collection of parameters for controlling the representation and appearance of text and graphics. For example, the graphic state can include a set of text attributes such as scale-factor, type-font, etc. In PostScript, an example of a PDL command used to build a graphic state can be: "twenty rotate," and "/Times-Roman findfont 14 scalefont setfont." Examples of PDL commands used to define the graphic or alpha-numeric data that is displayed in the data area include: 0 0 moveto and (ABC) show. The entire group of PDL commands used to define a document is hereinafter referred to as the "PDL specification."
In variable data printing each printed document shares a common template and there is at least one area in the template that changes for each printing of the template. Typical PDL languages are not designed for high-speed variable data printing because, with PDL languages and PDL interpreters, even if a single item of data in the document changes, an entirely new PDL specification must be created and interpreted. For example, if one-hundred thousand copies of a mass-mailing advertisement were to printed (i.e., each copy of which is identical except for the mailing address), it is typically necessary to generate a new PDL specification for each copy to printed. Hence, to generate one-hundred thousand advertisements, it would be necessary to generate one-hundred thousand PDL specifications, even though each advertisement is virtually the same except for the variable data area. The processing time required to interpret and render one-hundred thousand PDL specifications is enormous, significantly slowing the entire printing system.
Furthermore, typical PDL languages do not include any text or data flowing capabilities. These features are usually implemented by the application program, and when such an application program flows data (such as text) into a PDL document, the calculations to determine where to place the data are completed prior to the generation to the PDL specification. Accordingly, variable data cannot be flowed into a template document without creating a new PDL specification for each document. Accordingly, there is a need for a high-speed printing operation having the ability to merge variable data into a template defined by a PDL specification; and in particular, having the ability to flow variable data into a template path defined by PDL specification in a high-speed printing operation.